Resonant ZVS isolation boost circuit and control method thereof

Abstract

The invention discloses a resonant ZVS isolation boost circuit and a control method thereof. The resonant ZVS isolation boost circuit comprises an improved Royer resonance and transformation rectification circuit, a current hysteresis mode control circuit and a half-bridge switch circuit. Drain electrodes of a fifth NMOS tube and a sixth NMOS tube in the half-bridge switching circuit are led out to one end of a fourth inductor of the improved Royer resonance and transformation rectification circuit, and two ends of an output capacitor of the improved Royer resonance and transformation rectification circuit are connected to two input ends of a feedback control module of the current hysteresis mode control circuit. Source electrodes of a first NMOS tube and a second NMOS tube of the improved Royer resonance and transformation rectification circuit are connected to one end of a current detection resistor of the current hysteresis mode control circuit, a positive output end of an RS latch of the current hysteresis mode control circuit is connected to a positive input end of a half-bridge driving module in the half-bridge switching circuit, and a negative output end of the RS latch is connected to a negative input end of the half-bridge driving module. According to the invention, stable boost output can be realized under the condition of constant voltage input.

Description

Technical Field

[0001] The present invention relates to the technical field of isolated boost circuits, and in particular to a resonant ZVS isolated boost circuit and a control method thereof. Background Art

[0002] The traditional resonant ZVS isolated boost circuit has been around for a long time. The version that uses MOSFET as the switching device cleverly utilizes the current excitation characteristics of the LC parallel resonant circuit. The drain voltage waveform of the MOSFET is a half-sine wave. When its voltage passes through zero, the switch tube works alternately, which makes the MOSFET work in the ZVS state. It has the advantages of simple circuit, low loss, high oscillation frequency, and low interference. However, the traditional resonant ZVS isolated boost circuit has a circuit topology that does not have the ability to regulate voltage, so it cannot stabilize the output voltage, which limits its application range. In addition, the traditional resonant ZVS isolated boost circuit has a slow response speed to the input voltage, and there will be an imbalance in the volt-seconds at both ends of the transformer, which may cause core saturation. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a compact, reliable and efficient resonant ZVS isolation boost circuit and a control method thereof.

[0004] To achieve the above-mentioned purpose, the technical solution provided by the present invention is: a resonant ZVS isolation boost circuit, comprising an improved Royer resonance and transformer rectification circuit, a current hysteresis mode control circuit and a half-bridge switch circuit; the source of the fifth NMOS tube and the drain of the sixth NMOS tube in the half-bridge switch circuit are led to one end of the fourth inductor of the improved Royer resonance and transformer rectification circuit, the two ends of the output capacitor of the improved Royer resonance and transformer rectification circuit are connected to the two input ends of the feedback control module of the current hysteresis mode control circuit, the source of the first and second NMOS tubes of the improved Royer resonance and transformer rectification circuit are connected to one end of the current detection resistor of the current hysteresis mode control circuit, the positive output end of the RS latch of the current hysteresis mode control circuit is connected to the positive input end of the half-bridge drive module in the half-bridge switch circuit, and the negative output end is connected to the negative input end of the half-bridge drive module;

[0005] The improved Royer resonance and transformer rectification circuit includes first to fourth NMOS tubes, a resonant capacitor, first and second inductors on the primary side of the transformer, a third inductor and a fourth inductor on the secondary side of the transformer, first to fourth diodes for rectification, an output capacitor and an external first power supply; wherein the sources of the first and second NMOS tubes are connected, the gate of the first NMOS tube is connected to the source of the fourth NMOS tube, the drain of the first NMOS tube is respectively connected to the drain of the third NMOS tube and one end of the resonant capacitor, the gate of the second NMOS tube is connected to the source of the third NMOS tube, and the drain of the second NMOS tube is respectively connected to the drain of the fourth NMOS tube and the resonant capacitor The other end of the output capacitor is connected to the external first power supply, the gates of the third and fourth NMOS tubes are respectively connected, the two opposite-name ends of the first and second inductors are respectively connected to the two ends of the resonant capacitor, the other two opposite-name ends of the first and second inductors are connected and connected to the other end of the fourth inductor, the positive electrode of the first diode and the negative electrode of the third diode are connected to one end of the third inductor, the positive electrode of the second diode and the negative electrode of the fourth diode are connected to the other end of the third inductor, the negative electrodes of the first diode and the second diode are connected, and the positive electrodes of the third diode and the fourth diode are connected; the negative electrodes of the first diode and the second diode are connected to one end of the output capacitor, and the positive electrodes of the third diode and the fourth diode are connected to the other end of the output capacitor.

[0006] Furthermore, the current hysteresis mode control circuit includes a feedback control module, a current sensing resistor, a current sensing amplifier, a high-end comparator, a low-end comparator and an RS latch; the positive output end of the feedback control module is connected to the positive input end of the high-end comparator, and the negative output end is connected to the negative input end of the low-end comparator; the negative input end of the current sensing amplifier is grounded, and the positive input end is connected to the non-grounded end of the current sensing resistor; the R pin of the RS latch is connected to the output of the high-end comparator, the S pin is connected to the output of the low-end comparator, the positive output Q pin is connected to the positive input end of the half-bridge drive module in the half-bridge switch circuit, and the negative output / Q pin is connected to the negative input end of the half-bridge drive module.

[0007] Furthermore, the half-bridge switching circuit includes an external second power supply, a half-bridge driving module, and fifth and sixth NMOS tubes; the drain of the fifth NMOS tube is connected to the external second power supply, the gate is connected to the positive output of the half-bridge driving module, the source is connected to the drain of the sixth NMOS tube, the gate of the sixth NMOS tube is connected to the negative output of the half-bridge driving module, and the drain is grounded.

[0008] The present invention also provides a control method for the above-mentioned resonant ZVS isolation boost circuit, and the specific process is as follows:

[0009] Since the transformer resonance peak voltage of the improved Royer resonance and transformer rectification circuit is positively correlated with the current source current equivalent to the fourth inductor, in order to stabilize the output voltage of the improved Royer resonance and transformer rectification circuit, the current hysteresis mode control circuit and the half-bridge switch circuit need to effectively control the average current of the fourth inductor. For the improved Royer resonance and transformer rectification circuit, the current flows into one side of the fourth inductor and flows out from the ground terminals of the first and second NMOS tubes. For this reason, the current sensing resistor in the current hysteresis mode control circuit is connected to the original ground terminals of the first and second NMOS tubes. The voltage at both ends of the current sensing resistor is amplified by the current sensing amplifier and enters the high-end and low-end comparators to compare with the high-end and low-end comparators from the feedback control module in the current hysteresis mode control circuit. The two current threshold signals of the low-end comparator are compared; when the current detection signal output by the current detection amplifier reaches the current upper limit set by the feedback control module and the high-end and low-end comparators, the high-end comparator outputs a low level to the R pin of the RS latch, and the RS latch is reset, so that the half-bridge drive module in the half-bridge switch circuit controls the fifth NMOS tube to turn off and the sixth NMOS tube to turn on, and the current of the fourth inductor decreases at this time; when the current detection signal output by the current detection amplifier reaches the current lower limit set by the feedback control module and the high-end and low-end comparators, the low-end comparator outputs a low level to the S terminal of the RS latch, and the RS latch is set, so that the half-bridge drive module in the half-bridge switch circuit controls the fifth NMOS tube to turn on and the sixth NMOS tube to turn off, and the current of the fourth inductor increases at this time;

[0010] The above process is repeated continuously, and the current of the fourth inductor can be maintained between the upper and lower current limits set by the feedback control module and the high and low side comparators.

[0011] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0012] The present invention improves the traditional Royer oscillation circuit, effectively improves the switching rate of the switch NMOS tube in the improved Royer resonance and transformer rectification circuit, and greatly reduces the switching loss of the NMOS tube. In addition, compared with the general voltage mode control circuit, the current hysteresis mode control circuit of the present invention adds a current detection amplifier, and the input current can fluctuate within a set range, which solves the problem of inductance magnetic saturation at both ends of the intermediate tap of the primary measurement of the transformer, and improves the response speed of the output voltage of the improved Royer resonance and transformer rectification circuit to the input voltage.

[0013] The improved Royer resonance and transformer rectifier circuit significantly improves the conduction rate of the switch NMOS tube and reduces the switching loss by replacing the diode and resistor power supply mode with the source follower NMOS tube power supply mode. The current hysteresis mode control circuit adds current feedback to the original voltage feedback mode by means of a detection circuit, thereby improving the circuit's response rate to the input voltage. The present invention can achieve stable boost output under constant voltage input. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the resonant ZVS isolation boost circuit of the present invention.

[0015] Figure 2 This is the schematic diagram of the classic resonant Royer oscillator circuit.

[0016] Figure 3 This is the schematic diagram of the improved Royer resonance and transformer rectification circuit.

[0017] Figure 4 An explanatory schematic diagram of the classic resonant Royer oscillator circuit.

[0018] Figure 5 It is the S-domain equivalent block diagram of the center-tapped parallel resonant circuit.

[0019] Figure 6 This is the tapped LC resonant circuit current source excitation waveform.

[0020] Figure 7 It is a working waveform diagram of the resonant ZVS isolation boost circuit of the present invention.

[0021] Figure 8 This is a specific implementation schematic diagram of the feedback control module.

[0022] Fig. 9 It is a specific circuit diagram in practical application. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0024] like Figure 1 As shown, this embodiment discloses a resonant ZVS isolation boost circuit, including an improved Royer resonance and transformer rectification circuit I, a current hysteresis mode control circuit II and a half-bridge switch circuit III. The source of the fifth NMOS tube M5 and the drain of the sixth NMOS tube M6 in the half-bridge switch circuit III are led to one end of the fourth inductor L4 of the improved Royer resonance and transformer rectification circuit I, and the output capacitor C of the improved Royer resonance and transformer rectification circuit I is connected to the output capacitor C of the improved Royer resonance and transformer rectification circuit I. outThe two ends are connected to the two input ends of the feedback control module of the current hysteresis mode control circuit II, and the source of the first and second NMOS tubes M1 and M2 of the improved Royer resonance and transformer rectifier circuit I are connected to the current sensing resistor R s One end of the RS latch U1 of the current hysteresis mode control circuit II is connected to the positive input end of the half-bridge driving module in the half-bridge switch circuit III, and the negative output end is connected to the negative input end of the half-bridge driving module.

[0025] First use Figure 2 Explain the working process of the classic resonant Royer oscillator circuit: In the classic resonant Royer oscillator circuit, after the power source V2 with voltage source properties is connected in series with the fourth inductor L4, its properties are similar to those of a current source because the inductor current cannot change suddenly. After the power supply is turned on, the voltage V1 passes through R c , R d The gate voltage of NMOS tubes M1 and M2 begins to rise, and the two NMOS tubes are turned on alternately. Since the performance of components in the actual circuit cannot be completely consistent, the opening degree of the two NMOS tubes increases at different rates. When the opening degree of one NMOS tube reaches a large enough level first, the gate voltage of the other NMOS tube will be pulled down through one of the diodes D1 and D2. In this way, the two NMOS tubes are in a state where one is fully turned on and the other is completely turned off. After the circuit is stable, M1 and M2 are in an alternating conduction state.

[0026] The classic resonant Royer oscillator circuit has some defects. In the stable oscillation state, the diode here can be equivalent to a resistor under the AC oscillation voltage. c , R d , the equivalent input capacitance C of the first and second NMOS tubes M1 and M2 iss Together with the external first power supply V1, they form a first-order resistor-capacitor circuit. Therefore, in the classic resonant Royer oscillator circuit, the resonant capacitor C R When the voltage rises rapidly, the gate voltage of the NMOS tubes M1 and M2 rises very slowly, and the conduction rate is relatively slow, which may cause the voltage and current to exist simultaneously between the drain and source of the NMOS tube, increase power consumption, and damage the device. The most direct improvement method is to reduce the resistance between the gate of the NMOS tubes M1 and M2 and the power supply. However, if the resistance is directly reduced, the voltage of the gate of the NMOS tubes M1 and M2 may not be enough to drop to 0V and cannot be turned off. Therefore, on the basis of the classical resonant Royer oscillation circuit, the present invention further improves the gate drive circuit to obtain an improved Royer resonance and transformer rectification circuit I.

[0027] The improved Royer resonance and transformer rectification circuit I comprises first to fourth NMOS tubes M1, M2, M3, M4, a resonance capacitor C R , the first and second inductors L1 and L2 on the primary side of the transformer, the third inductor L3 and the fourth inductor L4 on the secondary side of the transformer, the first to fourth diodes D1, D2, D3, D4 for rectification, and the output capacitor C out and an external first power source V1; wherein the sources of the first and second NMOS tubes M1 and M2 are connected, the gate of the first NMOS tube M1 is connected to the source of the fourth NMOS tube M4, and the drain of the first NMOS tube M1 is respectively connected to the drain of the third NMOS tube M3 and the resonant capacitor C R The gate of the second NMOS tube M2 is connected to the source of the third NMOS tube M3, and the drain of the second NMOS tube M2 is connected to the drain of the fourth NMOS tube M4 and the resonant capacitor C R The other end of the external first power supply V1 is connected to the gate of the third and fourth NMOS tubes M3 and M4 respectively, and the two opposite ends of the first and second inductors L1 and L2 are connected to the resonant capacitor C R The other two opposite-name ends of the first and second inductors L1 and L2 are connected and connected to the other end of the fourth inductor L4. The positive electrode of the first diode D1 and the negative electrode of the third diode D3 are connected to one end of the third inductor L3. The positive electrode of the second diode D2 and the negative electrode of the fourth diode D4 are connected to the other end of the third inductor L3. The negative electrodes of the first diode D1 and the second diode D2 are connected, and the positive electrodes of the third diode D3 and the fourth diode D4 are connected. The negative electrodes of the first diode D1 and the second diode D2 are connected to the output capacitor C out The anodes of the third diode D3 and the fourth diode D4 are connected to the output capacitor C out the other end.

[0028] The improved Royer resonance and transformer rectification circuit I adds a pair of fourth and third NMOS transistors M4 and M3 working in source follower state to control the gate voltages of the first and second NMOS transistors M1 and M2 respectively. Figure 3As shown. From the gate of the NMOS tube M1 (or M2), when the voltage at point B (or A) rises rapidly, due to the nature of the source follower of the NMOS tube M4 (or M3), the gate of the NMOS tube M1 (or M2) is equivalent to being directly connected to the external first power supply V1; and when the voltage at point B (or A) is 0, there is a parallel equivalent diode in the NMOS tube equivalent model, which makes the gate voltage of the NMOS tube M1 (or M2) pulled down, and the shutdown process of the NMOS tube M1 (or M2) is consistent with the process of the classic resonant Royer oscillation circuit. In summary, it can be considered that the improved circuit reduces the resistance in the first-order RC circuit while enabling the gate voltage of the first and second NMOS tubes M1 and M2 to be pulled down normally. This circuit greatly improves the switching speed of M1 and M2 and further reduces its switching loss.

[0029] Next, under stable conditions, the oscillation process of the improved Royer resonance and transformer rectifier circuit I is qualitatively explained.

[0030] First, at the moment when D is fully turned on and C is fully turned off: the current IB flowing through L2 reaches the maximum value of the sinusoidal waveform, and the current IA flowing through L1 reaches the minimum value of the sinusoidal waveform; the current IA (> 0) flows from the middle capacitor to the right to charge, VA starts to rise from 0, and VD rises accordingly (stops rising when VD = Vdd). The current IB (< 0) flows from the middle capacitor to the right to charge. Since the D tube is fully turned on, VB = 0, which turns off the C tube.

[0031] IA rises and IB falls until IA=IB=0: the voltage VA reaches its maximum, which makes VD reach its maximum and the D tube remains on.

[0032] IA continues to rise, and IB continues to fall until the D tube begins to cut off. The voltage VA begins to fall, the voltage VD begins to fall, and the capacitor discharges in the reverse direction. The D tube begins to cut off, driving VB to rise, and then driving VC to rise, and then the voltage across the capacitor is 0. According to the charging direction of the capacitor, VB rises, and the C tube begins to conduct.

[0033] IA continues to rise and IB continues to fall until IA reaches the maximum value of the sinusoidal voltage and IB reaches the minimum value. At this time, C is fully turned on and D is completely turned off, forming a half cycle.

[0034] According to the qualitative analysis of the alternating switching process of the transistor in the above stabilization process, it can be found that the improved Royer resonance and transformer rectifier circuit I flips just when the absolute value of the current IA or IB reaches a maximum value, so that the current source can continuously input energy to the improved Royer resonance and transformer rectifier circuit I at the appropriate position in each half cycle, and finally the output voltage can be continuously increased.

[0035] Since the first and second NMOS tubes M1 and M2 are turned on alternately, each turn-on alternation is equivalent to the improved Royer resonance and transformer rectification circuit I, the transformer primary is measured by the first and second inductors L1 and L2, and the resonant capacitor C R The tapped LC resonant circuit is excited by the step current source, so the improved Royer resonance and transformer rectifier circuit I can be equivalent to Figure 4 To explain, R eq Used to equalize the load effect produced by the secondary of a transformer.

[0036] Next, the improved Royer resonance and transformer rectifier circuit I is quantitatively analyzed. Figure 4 After the circuit is linearized, the circuit is analyzed from the Laplace transform domain (hereinafter referred to as the s domain, s is the complex number of the Laplace transform complex frequency domain), and the following equation can be obtained, where the voltage v1 is the voltage at the non-grounded point at both ends of L1 and L2, and the voltage V M is the voltage of the middle tap of L1 and L2, L1 is the inductance value of inductor L1, L2 is the inductance value of inductor L2, M is the mutual inductance value between inductors L1 and L2, C R is the inductor C R The inductance value, R eq is the equivalent resistance R eq The resistance value, I in For the equivalent input current, the voltage v1 can be calculated using equation (1):

[0037]

[0038] Solving the above equation, we can get Figure 5 The block diagram of linear representation in the s domain is shown, K is the inductance proportional coefficient, and the algebraic expression of the voltage v1 in the s domain is calculated. Then, the time domain expression function of the voltage v1 under the step response current can be obtained according to the Laplace transform table. According to the time domain expression function of the voltage v1, it is found that the voltage v1 is just a decaying sine wave. For the convenience of representation, let C = C R , R = R eq , L = L2 + M, V = v1, t is the time in seconds. The time domain expression function V(t) of voltage V = v1 can be obtained as follows.

[0039]

[0040] Under the excitation of the step current source, due to the characteristics of the LC parallel resonant circuit, the voltage at the ungrounded end will present a decaying sinusoidal resonant waveform, starting from 0 voltage and rising in a sinusoidal waveform, returning to zero after passing the highest point of the resonant voltage, such as Figure 6As shown. In the improved Royer resonance and transformer rectification circuit I, taking M2 turned on and M1 turned off as an example, the drain voltage waveform of M1 will experience a process from 0V to the resonance voltage peak and then to 0V. But when the drain voltage of M1 drops to 0V, the gate of M2 is pulled down to turn it off. At the same time, M2 releases the other end of the LC resonant circuit, and the gate of M1 is no longer pulled down, so that M1 can be fully turned on and enter the next cycle, so the oscillation can be maintained. The actual waveform is shown in Figure 7 As shown, V(vc) is the control voltage waveform of the half-bridge driving module in the half-bridge switch circuit III, I(L5) is the current waveform flowing through the fourth inductor L4, V(vo) is the output voltage waveform of the improved Royer resonance and transformer rectifier circuit I, V(d1) is the drain waveform of the first NMOS tube M1, V(d2) is the drain waveform of the second NMOS tube M2, V(g1) is the gate waveform of the first NMOS tube M1, and V(g2) is the gate waveform of the second NMOS tube M2.

[0041] The current hysteresis mode control circuit II includes a feedback control module, a current sensing resistor R S , current-sense amplifier CsAmp, high-end comparator cmpH, low-end comparator cmPL and RS latch U1; the positive output of the feedback control module is connected to the positive input of the high-end comparator cmpH, the negative output is connected to the negative input of the low-end comparator cmPL, the negative input of the current-sense amplifier CsAmp is grounded, and the positive input is connected to the current-sense resistor R s The non-grounded end of the RS latch U1, the R pin of the RS latch U1 is connected to the output of the high-end comparator cmpH, the S pin is connected to the output of the low-end comparator cmpL, the positive output Q pin is connected to the positive input terminal of the half-bridge driving module in the half-bridge switching circuit III, and the negative output / Q pin is connected to the negative input terminal of the half-bridge driving module.

[0042] The half-bridge switch circuit III includes an external second power supply V2, a half-bridge driving module, and a fifth and sixth NMOS tubes M5 and M6; the drain of the fifth NMOS tube M5 is connected to the external second power supply V2, the gate is connected to the positive output of the half-bridge driving module, the source is connected to the drain of the sixth NMOS tube M6, the gate of the sixth NMOS tube M6 is connected to the negative output of the half-bridge driving module, and the drain is grounded.

[0043] Since the transformer resonance peak voltage of the improved Royer resonance and transformer rectifier circuit I is positively correlated with the current source current equivalent to L4, in order to stabilize the output voltage of circuit I, circuits II and III should be able to effectively control the average current of L4. For circuit I, the current flows into one side of the inductor L4 and must flow out from the ground terminal of the first and second MOS tubes, so a low-cost and easy-to-implement low-side current detection solution can be adopted. For this purpose, the current detection resistor R in the current hysteresis mode control circuit II is connected to the original ground terminal of the first and second NMOS tubes M1 and M2 of circuit I. s , the voltage at both ends is amplified by the current-sense amplifier CsAmp, and then enters the high-end and low-end comparators CmpH and CmpL, and is compared with the two current threshold signals from the feedback control module and the high-end and low-end comparators CmpH and CmpL in circuit II. When the current-sense signal output by the current-sense amplifier CsAmp reaches the current upper limit set by the feedback control module and the high-end and low-end comparators CmpH and CmpL, CmpH outputs a low level to the R end of the RS latch U1, so that U1 is reset, and the half-bridge drive module in circuit III controls M5 to turn off and M6 to turn on, at which time the current of L4 decreases; when the current-sense signal output by CsAmp reaches the current lower limit set by the feedback control module and the high-end and low-end comparators CmpH and CmpL, CmpL outputs a low level to the S end of the RS latch U1, so that U1 is set, so that the half-bridge drive module in circuit III controls M5 to turn on and M6 to turn off, and at this time the current of L4 increases. The above process is repeated continuously, and the current of L4 can be maintained to fluctuate between the upper and lower current limits set by the feedback control module and the high and low end comparators CmpH and CmpL. Compared with the general voltage mode control circuit, this current hysteresis mode control circuit II adds a current detection amplifier to prevent the problem of excessive peak current. In order to ensure that the circuit voltage of the output part is a constant value, the general voltage mode control circuit will use the feedback of the output voltage to adjust the voltage, and use the partial feedback circuit connected to the input to adjust the constant current of the Royer oscillation circuit. This current hysteresis mode control circuit II can improve the response speed of the output voltage of the improved Royer resonance and transformer rectification circuit I to the input voltage change: if the voltage mode control circuit is used, when the input voltage fluctuates, the change of the input voltage needs to wait until the output changes before it can be fed back to the half-bridge drive; with the current detection comparator CsAmp, the input voltage increase will cause the input current slope to increase, and the change of the current slope will be fed back to the half-bridge switch circuit III, which improves the response speed of the system.

[0044] The feedback control module in the current hysteresis mode control circuit II can be composed of Figure 8 Given. Figure 8 In, V outRepresents the voltage output by the circuit. This voltage is a constant value when the circuit is stable. R2 and R3 are voltage divider resistors. Generally, R2 is much larger than R3. The voltage on R2 provides a voltage reference for the controllable precision voltage regulator D5. According to the description in the TL431A data sheet, the controllable precision voltage regulator has a built-in 2.5V reference voltage. When the reference voltage of D5 on its right side is greater than 2.5V, the cathode voltage of D5 becomes 0, which turns on the optocoupler circuit on the left, reducing the positive and negative output voltages V of the feedback control module. fbH 、V fbL , reducing the current in the Royer oscillation circuit, making the voltage V out When the reference voltage of the right side of D5 is less than 2.5V, the cathode voltage of D5 becomes 5V, which turns on the left side optocoupler circuit and increases V fbH 、V fbL , reducing the current in the Royer oscillation circuit, making the voltage V out Therefore, the voltage V can be divided by resistors R2 and R3. out The control formula of the output voltage by the resistor is as follows, where V ref The internal reference voltage of the voltage regulator. Figure 8 The feedback control module uses V ref The value is 2.5V.

[0045]

[0046] Figure 8 The feedback control module given will convert V out The voltage divided to the reference voltage of the controllable precision voltage regulator D5 is transmitted to the circuit on the left through the optocoupler. out When the voltage reaches the lower limit of 400V, the optocoupler turns on and V fbH 、V fbL The high-side comparator cmpH of the current hysteresis mode control circuit II outputs a high level, the low-side comparator cmpL outputs a low level, the RS latch is set, and the half-bridge drive module starts to provide energy for the improved Royer resonance and transformer rectifier circuit I, and the output voltage rises; when the output voltage V out When the voltage reaches the upper limit of 400V, the optocoupler is turned off, and V fbH 、V fbL rises, the high-side comparator cmpH outputs a low level, the low-side comparator cmpL outputs a high level, the RS latch is reset, and the half-bridge drive module stops providing energy to the improved Royer resonance and transformer rectifier circuit I; when the output voltage V out When the target output voltage is near, the optocoupler is partially turned on, V fbH 、V fbLThe value of makes the high and low side comparators cmpH and cmpL output high level at the same time, and the RS latch maintains the previous state. In this way, the circuit can output a stable DC voltage.

[0047] Finally, the actual circuit schematic is as follows Fig. 9 shown.

[0048] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A resonant ZVS isolation boost circuit, characterized in that: The invention comprises an improved Royer resonance and transformer rectification circuit (I), a current hysteresis mode control circuit (II) and a half-bridge switch circuit (III); the source of a fifth NMOS tube (M5) and the drain of a sixth NMOS tube (M6) in the half-bridge switch circuit (III) are led to one end of a fourth inductor (L4) of the improved Royer resonance and transformer rectification circuit (I), and the output capacitor (C out ) are connected to two input ends of the feedback control module of the current hysteresis mode control circuit (II), and the source electrodes of the first and second NMOS tubes (M1, M2) of the improved Royer resonance and transformer rectification circuit (I) are connected to the current sensing resistor (R s ), the positive output end of the RS latch (U1) of the current hysteresis mode control circuit (II) is connected to the positive input end of the half-bridge driving module in the half-bridge switch circuit (III), and the negative output end is connected to the negative input end of the half-bridge driving module; The improved Royer resonance and transformer rectification circuit (I) comprises first to fourth NMOS tubes (M1, M2, M3, M4), a resonance capacitor (C R ), the first and second inductors (L1, L2) on the primary side of the transformer, the third inductor (L3) and the fourth inductor (L4) on the secondary side of the transformer, the first to fourth diodes (D1, D2, D3, D4) for rectification, and the output capacitor (C out ) and an external first power supply (V1); wherein the sources of the first and second NMOS tubes (M1, M2) are connected, the gate of the first NMOS tube (M1) is connected to the source of the fourth NMOS tube (M4), and the drain of the first NMOS tube (M1) is respectively connected to the drain of the third NMOS tube (M3) and the resonant capacitor (C R ), the gate of the second NMOS tube (M2) is connected to the source of the third NMOS tube (M3), and the drain of the second NMOS tube (M2) is respectively connected to the drain of the fourth NMOS tube (M4) and the resonant capacitor (C R ), the other end of the external first power supply (V1) is connected to the gate of the third and fourth NMOS tubes (M3, M4), and the two opposite ends of the first and second inductors (L1, L2) are connected to the resonant capacitor (C R ), the other two opposite-named ends of the first and second inductors (L1, L2) are connected and connected to the other end of the fourth inductor (L4), the positive electrode of the first diode (D1) and the negative electrode of the third diode (D3) are connected to one end of the third inductor (L3), the positive electrode of the second diode (D2) and the negative electrode of the fourth diode (D4) are connected to the other end of the third inductor (L3), the negative electrodes of the first diode (D1) and the second diode (D2) are connected, and the positive electrodes of the third diode (D3) and the fourth diode (D4) are connected; the negative electrodes of the first diode (D1) and the second diode (D2) are connected to the output capacitor (C out ), the anodes of the third diode (D3) and the fourth diode (D4) are connected to the output capacitor (C out ) at the other end.

2. The resonant ZVS isolation boost circuit according to claim 1, characterized in that: The current hysteresis mode control circuit (II) comprises a feedback control module, a current sensing resistor (R s ), a current-sense amplifier (CsAmp), a high-end comparator (cmpH), a low-end comparator (cmpL) and an RS latch (U1); the positive output end of the feedback control module is connected to the positive input end of the high-end comparator (cmpH), and the negative output end is connected to the negative input end of the low-end comparator (cmpL); the negative input end of the current-sense amplifier (CsAmp) is grounded, and the positive input end is connected to the current-sense resistor (R s ) non-grounded end; the R pin of the RS latch (U1) is connected to the output of the high-end comparator (cmpH), the S pin is connected to the output of the low-end comparator (cmpL), the positive output Q pin is connected to the positive input end of the half-bridge driving module in the half-bridge switch circuit (III), and the negative output / Q pin is connected to the negative input end of the half-bridge driving module.

3. The resonant ZVS isolation boost circuit according to claim 2, characterized in that: The half-bridge switch circuit (III) comprises an external second power supply (V2), a half-bridge driving module and fifth and sixth NMOS tubes (M5, M6); the drain of the fifth NMOS tube (M5) is connected to the external second power supply (V2), the gate is connected to the positive output of the half-bridge driving module, the source is connected to the drain of the sixth NMOS tube (M6), the gate of the sixth NMOS tube (M6) is connected to the negative output of the half-bridge driving module, and the drain is grounded.

4. The control method of the resonant ZVS isolation boost circuit according to any one of claims 1 to 3, characterized in that: The specific process is as follows: Since the transformer resonance peak voltage of the improved Royer resonance and transformer rectification circuit (I) is positively correlated with the current source current equivalent to the fourth inductor (L4), in order to stabilize the output voltage of the improved Royer resonance and transformer rectification circuit (I), the current hysteresis mode control circuit (II) and the half-bridge switch circuit (III) need to effectively control the average current of the fourth inductor (L4). For the improved Royer resonance and transformer rectification circuit (I), the current flows into one side of the fourth inductor (L4) and flows out from the grounding terminal of the first and second NMOS tubes (M1, M2). Therefore, the current detection resistor (R s ), the voltage at both ends of the current sense amplifier (CsAmp) is amplified and enters the high-end and low-end comparators (CmpH, CmpL), and is compared with the two current threshold signals from the feedback control module and the high-end and low-end comparators (CmpH, CmpL) in the current hysteresis mode control circuit (II); when the current sense signal output by the current sense amplifier (CsAmp) reaches the current upper limit set by the feedback control module and the high-end and low-end comparators (CmpH, CmpL), the high-end comparator (CmpH) outputs a low level to the R pin of the RS latch (U1), and the RS latch (U1) is reset, so that the half-bridge switch circuit (III) The half-bridge driving module controls the fifth NMOS tube (M5) to turn off and the sixth NMOS tube (M6) to turn on, and the current of the fourth inductor (L4) decreases; when the current detection signal output by the current detection amplifier (CsAmp) reaches the current lower limit set by the feedback control module and the high-end and low-end comparators (CmpH, CmpL), the low-end comparator (CmpL) outputs a low level to the S end of the RS latch (U1), and the RS latch (U1) is set, so that the half-bridge driving module in the half-bridge switch circuit (III) controls the fifth NMOS tube (M5) to turn on and the sixth NMOS tube (M6) to turn off, and the current of the fourth inductor (L4) increases; The above process is repeated continuously, and the current of the fourth inductor (L4) can be maintained between the upper and lower current limits set by the feedback control module and the high and low side comparators (CmpH, CmpL).

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